Pathophysiological processes that affect the brain produce alterations of metabolites which can be detected by Magnetic Resonance Spectroscopy (MRS). The goals of this project are to develop improved MR spectroscopic imaging (SI) techniques to measure the distribution of these metabolites in vivo and to evaluate MR SI techniques for diagnosis and prognosis of stroke. 1H and 31P MR SI techniques are proposed for the observation of lactate, amino acids (N-Acetylaspartate, Glutamate, Taurine, GABA) and other metabolite distributions. Alteration of in vivo metabolite distributions with temporary and permanent focal cerebral ischemia will be monitored in the rat. These studies will investigate i) the importance of lactate as a marker of ischemia, ii) that decreased NAA is a marker of neuronal damage, and iii) increased levels of glutamate and other Excitatory Amino Acids cause delayed tissue damage. Results of this work will be incorporated within ongoing clinical spectroscopy studies of stroke. Improvements to the Fourier method of spectroscopic imaging are proposed, including; i) increasing the information content of the SI acquisition using short TE, spin editing and 3D imaging, ii) improved data processing to remove a number of instrumental problems, iii) improved spectral analysis techniques for quantitation of metabolite concentrations. Processing and display utilities will be further developed to facilitate rapid analysis and review of SI data.